NTSB · Safety Recommendation
Safety Recommendation A-18-013
Recommendation
TO THE FEDERAL AVIATION ADMINISTRATION: Although controlled flight into terrain (CFIT)-avoidance training programs are not required by federal regulation for Title 14 Code of Federal Regulations Part 135 fixed-wing operations, work with Part 135 operators in Alaska to improve any voluntarily implemented training programs aimed at reducing the risk of CFIT accidents involving continuation of flight under visual flight rules (VFR) into instrument meteorological conditions, with special attention paid to the human factors issues identified in recent Alaska accident investigations, including, but not limited to, (1) the challenges of flying in mountainous terrain in Alaska and low-altitude VFR flight in an area subject to rapid changes in weather; and (2) limitations of the Alaska infrastructure, particularly weather observations, communications, and navigation aids.
Safety Issue and Context
On October 2, 2016, about 1157 Alaska daylight time, Ravn Connect flight 3153, a turbine-powered Cessna 208B Grand Caravan airplane, N208SD, collided with steep, mountainous terrain about 10 nautical miles northwest of Togiak Airport (PATG), Togiak, Alaska. The two commercial pilots and the passenger were killed, and the airplane was destroyed. The scheduled commuter flight was operated under visual flight rules (VFR) by Hageland Aviation Services, Inc., Anchorage, Alaska, under the provisions of Title 14 Code of Federal Regulations (CFR) Part 135.
The National Transportation Safety Board’s (NTSB) investigation determined that instrument meteorological conditions (IMC) were likely in the vicinity of the accident site at the time of the accident. The flight departed Quinhagak Airport, Quinhagak, Alaska, at 1133 and was en route to PATG. Data available for the accident flight showed that, after departure in visual meteorological conditions, the airplane proceeded along a generally direct route toward the destination at an altitude of about 1,000 ft mean sea level (msl), which resulted in terrain clearances between 500 and 700 ft above ground level (agl).
During the last 4 minutes of the flight, the airplane climbed as it approached the mountain ridge that it eventually struck at an elevation of about 2,300 ft msl after having likely entered IMC. The airplane was equipped with a Class B terrain awareness and warning system (TAWS) that had an en route required terrain clearance (RTC) of 700 ft agl; flight at altitudes below the RTC (and not within 15 miles of an airport, given certain criteria) would result in TAWS terrain alerts. Hageland flights operated under VFR were allowed to fly as low as 500 ft agl, as was seen with this flight, which was flown en route below the TAWS alerting threshold.
The system was equipped with a terrain inhibit switch that allowed the pilot to manually inhibit all TAWS aural and visual caution and warning alerts. A TAWS simulation that used an estimated flightpath for the accident airplane (assuming a level cruise altitude between known data points and a climb after the last data point to the accident elevation) showed that, if the alerts were not inhibited, the TAWS would have provided continuous alerts for most of the assumed flight. The investigation concluded that the TAWS alerts were likely inhibited for most, if not all, of the flight, eliminating a margin of safety.
Response History
December 13, 2024 · NTSB Correspondence · FAA
We note that, on June 11, 2021, the General Aviation Joint Steering Committee published its CFIT final report, which recommended safety enhancements (SEs) aimed at reducing the risk of CFIT accidents, including the following improvements to training:
• SE 52 recommends reviewing and updating the WINGS Pilot Proficiency Program’s training content to ensure it is current and includes CFIT-specific information from the CFIT Working Group’s efforts.
• SE 53 recommends reviewing existing measures intended to address pressure to complete a flight and identifying new opportunities for improved education and outreach to the flying community on the importance of managing pressure.
• SE 56 recommends forming an Unintended Entry Into Instrument Meteorological Conditions (UIMC) Escape Response Task Force to review past loss-of-control analysis and Aviation Safety Reporting System data involving UIMC and recommend improvements to training associated with responding to and escaping UIMC, such as an initial climb before any heading change, should the data support such a change.
• SE 58 recommends conducting an educational campaign and/or developing learning modules to educate instrument-current pilots about the safety benefits of backing up a nighttime VFR approach with lateral and vertical navigation guidance, particularly in mountainous terrain.
We also note that the FAA Safety Team (FAAST) educates pilots on how to recognize warning signs and precursors to CFIT accidents and incidents and reemphasizes key concepts of the SEs in recurrent training. In addition, the FAAST collaborates with the general aviation community and air carriers in Alaska during preseason and postseason meetings to share new developments and best practices for avoiding CFIT. We further note that the FAA Alaska Aviation Safety Initiative (FAASI) works with the Alaska aviation community to address safety issues that are unique to that state.
We believe the ongoing work of the FAAST and FAASI are positive. However, because the FAAST’s efforts typically focus on Part 91